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Kepler Guest Observer Program

Data Inspection and Analysis Tools

Kepler data is encoded using the Flexible Image Transport System (FITS). General FITS documentation is maintained by the Office for Guest Investigator Programs (OGIP) FITS Support Office at NASA GSFC. A primer on the FITS format can be found here. Each Kepler FITS product contains a combination of header keywords containing scalar data, time-dependent data stored as tables and/or detector pixel-level data stored as two-dimensional images. The content and format of each file are defined in the Kepler Archive Manual.


DATA VISUALIZATION

A variety of free software exists for FITS data inspection. While by know means a complete list, we have found the tools listed here to be of most common employment in our own inspection of the Kepler data:

FV: Software for display and editing FITS format tables and images, developed and distributed by NASA's High Energy Astrophysics Science and Archive Research Center. FV has proved to be the most efficient tool for inspecting Kepler's target pixel files. An example is provided here here. Versions are available for Unix, Linux, Mac OS and Windows platforms. Source code or binaries can be obtained here..

TOPCAT: Tool for Operation on Catalogs and Tables, a Java-based interactive graphical viewer and editor for tabular data. We have found this to be the most convenient, powerful and useful software for inspection of Kepler light curve files. An example of TOPCAT inspection of a light curve product is provided here. TOPCAT can be obtained here.

DS9: SAOImage DS9 is an image visualization application, developed by the Smithsonian Astrophysical Observatory. DS9 can display and compare multiple images together and contains scaling and zoom options. We have founds DS9 to be of most employment inspecting Kepler's Full Frame Images. An example is provided here. DS9 source code and binaries can be found here.

KeplerFFI: This FFI inspection tool is used to examine the sources surrounding a target, assess crowding, identify artifacts, and understand the effects of the photometric aperture on the light curves. KeplerFFI also creates a custom pixel mask by allowing users to select pixels for inclusion within a target aperture. Individual pixels are chosen interactively by tapping upon them. The standalone python tool is available for download here.

MAST FFI VIEWER: MAST maintains am online FFI display tool, which allows the user to examine individual channels within an FFI image. Kepler targets, as well as 2MASS and GALEX sources located within the frame are marked with symbols and user-selectable. Sources for which the data have been published or made public are also indicated.


DATA REDUCTION

PyKE: The Kepler archive contains raw and calibrated time-series data in both light curve and pixel form. This pipelined reduction includes the removal of time-series trends systematic to the spacecraft and its environment rather than the targets. For every target there is a level of subjectivity required to reduce systematics. Differing scientific goals are likely to have differing requirements for systematic mitigation. Systematic reduction in the Kepler pipeline is optimized to yield the highest number of potentially-detectable exoplanet transits from a sample of 160,000 stars. PyKE, on the other hand, is a group of python tasks developed for the reduction and analysis of Kepler Simple Aperture Photometry (SAP) data of individual targets with individual characteristics. PyKE was developed to provide alternative data reduction, tunable to the user's specific science goals. The main purposes of these tasks are to i) re-extract light curves from manually-chosen pixel apertures and ii) cotrend and/or detrend the data in order to reduce or remove systematic noise structure using methods tun-able to user and target-specific requirements. Tasks to perform data analysis developed for the author's science programs are also included. PyKE is an open source project. Contributions of new tasks or enhanced functionality of existing tasks by the community are welcome. PyKE can be installed on all PYRAF supported platforms from here.


DATA ANALYSIS

Here we provide links to publicly available software that may be useful to GOs and archive users for the interpretation of photometric time series. We invite users and developers to suggest more resources to add to this list.

PERIOD04: Period04 is designed for the statistical analysis of large astronomical time series. Developed by Patrick Lenz and Michel Breger at the University of Vienna, Period04 supports the Theory and Observation of Pulsating Stars (TOPS) Group. This software contains tools to identity power within time series and perform multi-frequency fitting. Period04 is a hybrid Java/C++ program. Execution requires the Java Runtime Environment (JRE) on your local machine. JRE is pre-installed on MacOS X platforms, Windows and Linux options are also available.
Point of Contact: Patrick Lenz, Institute of Astronomy, University of Vienna
Reference : P. Lenz and M. Breger, 2005, Period04 User Guide, Communications in Asteroseismology, 146, 53
Webpage: Period4

VARTOOLS: A command line utility that provides tools for calculating variability/periodicity statistics of light curves as well as tools for modifying light curves. The program is run by issuing a sequence of commands to perform actions on light curves, each command is executed in turn with the resulting light curves passed to the next command. Statistics computed by each command are sent to stdout as an ascii table.
Point of Contact: Joel Hartman, Princeton University
Reference : Hartman et al. (2008)
Webpage: VARTOOLS

AMP: The Asteroseismic Modeling Portal is an interface maintained by the National Center for Atmospheric Research (NCAR). AMP provides astronomers access to the software and resources needed for computationally intense research in stellar seismology. In particular, tools are available for astronomers wanting to utilize the Aarhus Stellar Evolution Code, coupled with a parallel genetic algorithm to derive the properties of Sun-like stars from observations of their pulsation frequencies. Users can (a), submit a list of measured properties and determine the best-fitting stellar model, or (b), specify a set of stellar parameters, and execute evolutionary models. Much of the motivation for development of AMP is the large increase in asteroseismic data now being delivered by Kepler. AMP represents an effort to develop a robust stellar model-fitting pipeline for asteroseismic data.
Point of Contact: Travis Metcalfe, National Center for Atmospheric Research
Reference: The AMP User's Guide can be found here, refereed article here: Metcalfe, Creevey & Christensen-Dalsgaard (2009)
Webpage: AMP

FAMIAS: An acronym for Frequency and Mode Identification for Asteroseismology, FAMIAS is a suite of software tools for the analysis of photometric and spectroscopic time series data. This software is provided by the European Coordination Action in Helio- and Asteroseismology (HELAS). Two main sets of tools are contained within FAMIAS. The first set allows users to search for periodicities in their data using Fourier and non-linear least-squares fitting algorithms. The other set can be used to identify modes for the detected pulsation frequencies, and determine their pulsation quantum numbers. FAMIAS tools are applicable to all pulsating main-sequence stars with T(eff) > 5500 K. FAMIAS can be implemented on Linux and MacOS X platforms.
Point of Contact: Wolfgang Zima, Instituut voor Sterrenkunde, Leuven, Belgium
Reference: W. Zima, 2008, FAMIAS User Manual, Communications in Asteroseismology, 155, 121
Webpage: FAMIAS, User Manual

PHOEBE: An acronym for PHysics Of Eclipsing BinariEs, PHOEBE is a software package designed for the modeling of eclipsing binary stars, combining observed photometric and spectroscopic data. PHOEBE contains a core library of functions, models, and problem solvers, accessed through either a user interface or a terminal-window scripting program. Its functionality enables users to combine a variety of techniques to constrain the physical properties of the modeled system with minimal technical effort. This software can be installed on various flavors of LINUX, MacOS, Windows XP and Vista.
Point of Contact: Andrej Prsa, Villanova University
Reference: PHOEBE Documentation, Prsa & Zwitter (2005)
Webpage: PHOEBE

TAP and autoKep: An IDL package designed for the analysis of extrasolar planet (ESP) transit light curves. The Transit Analysis Package (TAP) software utilizes Markov Chain Monte Carlo (MCMC) techniques to fit transit light curves using the Mandel & Agol (2002) model. The software is able to simultaneously analyze multiple transits observed in different conditions (instrument, filter, weather, etc). The graphical interface allows for the simple execution and interpretation of Bayesian MCMC analysis tailored to a user’s specific data set and has been thoroughly tested on ground-based and Kepler photometry. The autoKep IDL GUI is designed to provide streamlined transit light curves from MAST Kepler archive fits files.
Point of Contact: Zach Gazak, University of Hawaii Institute for Astronomy
Reference:
Webpage: TAP

JKTEBOP: Used to fit a model to the light curves of detached eclipsing binary stars in order to derive the radii of the stars as well as various other quantities. It includes Monte Carlo or bootstrapping error analysis algorithms. It is also suitable for transiting extrasolar planetary systems.
Point of Contact: John Southworth, Keele University
Reference: Southworth, Maxted and Smalley (2004)
Webpage: JKTEBOP

SOAP-T: Generates the radial velocity variations and light curves for systems consisting of a rotating, spotted star with a transiting planet. This tool can be used to study the anomalies inside transit light-curves and the Rossiter-McLaughlin effect, to better constrain the orbital configuration and properties of planetary systems and active zones of their host stars.
Point of Contact: Mahmoudreza Oshagh, University of Porto
Reference: Oshagh et al. (2013)
Webpage: SOAP-T

FITSH: This software package provides a set of independent binary programs that are designed for execution from a UNIX command line shell or shell script. Each of these tasks performs a specific operation (e.g. transforming an image to another reference frame, search and identifiy stars or other point-like sources, do photometry, transform/display a FITS image to a popular graphics format, ...) while the details of a certain operation are specified via command switches and arguments. Therefore this package does not need any higher level operating environment than a standard UNIX shell, however, processing the related data might require a little more knowledge of the used shell itself.
Point of Contact: Andras Pal, Konkoly Observatory of the Hungarian Academy of Sciences
Reference: Pal (2012)
Webpage: FITSH


FITS LIBRARIES

Scripting languages provide both FITS I/O libraries and data processing algorithms, allowing users to develop their own data analysis scripts for Kepler data. An extensive list of FITS I/O libraries is maintained by the FITS Support Office at NASA Goddard Space Flight Center. We list below those that we in the GO Office have familiarity with and can provide a degree of support.

PyFITS: Python is a freeware scripting language available for Unix, Linux, Mac OS and Windows platforms. PyFITS is an external python library that provides an interface to FITS formatted files. PyFITS is developed by the Science Software Branch at the Space Telescope Science Institute as support for their PyRAF development. PyRAF allows Python scripters to use the full functionality of IRAF libraries within the more powerful framework of Python. This will be the software environment for James Webb Space Telescope data reduction.

CFITSIO: NASA's High Energy Astrophysics Science Archive Research Center provides a library of algorithms for FITS I/O. Download instructions and programmers guide can be found at the HEASARC software pages. Originally written for C and FORTRAN programmers, there are now many interfaces provided for download that provide libraries for C++, C-sharp, Perl, Tcl, Python, Ruby, S-lang, Matlab and Labview.


Questions concerning Kepler's science opportunities and open programs, public archive or community tools? Contact us via the email address.
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Editor: Martin Still
NASA Official: Jessie Dotson
Last Updated: Jan 11, 2013
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